Answer this question truthfully
### Question: Who is at highest risk for Pneumocystis jirovecii pneumonia ?
### Response: This type of pneumonia is caused by the fungus Pneumocystis jiroveci. This fungus is common in the environment and does not cause illness in healthy people. However, it can cause a lung infection in people with a weakened immune system due to:
Cancer Chronic use of corticosteroids or other medications that weaken the immune system HIV/AIDS Organ or bone marrow transplant